A tire is manufactured from various types of tire constituent members which are sheet-shaped rubber members. During manufacture of a tire, a carcass ply is wound around a forming drum, for example. After that, a leading end portion and a rear end portion of the carcass ply are abutted to each other and joined together by a joining device so as to form a cylindrical carcass ply. As this kind of joining device, a device for automatically joining end portions of a rubber member together by a pair of joining rollers has been known (See Patent Literature 1).
In the prior-art joining device, the pair of joining rollers is moved along the end portions of the rubber member. The end portions of the rubber member are joined together by the pair of joining rollers. However, with this joining device, since the end portions are joined on one of surfaces of the rubber member, the end portions cannot be joined together from the both surfaces. As a result, there might be a difference in joining strength of the end portions between one surface and the other surface of the rubber member. Therefore, in view of joining of the end portions more firmly, there is a room for improvement. Particularly, in recent years, strength of the rubber member needs to be ensured in response to a trend to light-weighted tires. With this trend, increasing in joining strength of the end portions is in demand.
In addition, with the prior-art joining device, the size of the entire device becomes large and control becomes complicated. Thus, a cost for the device increases. A large space is also needed for installation of the device. In response to time required for the work of the joining device, a cycle time of a joining work becomes longer. There is also a problem that even while the joining device is not in use, since the joining device remains in a tire forming device, space is occupied by the joining device. Moreover, since a lot of labor is required for movement of the joining device, it is difficult to share the joining device in a plurality of tire forming devices. In order to cope with each of the above-described problems, easy and reliable joining of the end portions of the rubber member is in demand.
As the rubber member joining device, a device for joining end portions from both surfaces of a rubber member has been also known (See Patent Literatures 2 and 3).
However, these prior-art joining devices use a large-sized mechanism for moving a joining roller. Thus, the size of the entire device becomes large and control becomes complicated. That is, simple joining of the end portions cannot be realized, and it is difficult to solve the above-described problems.
The end portions can be joined on the both surfaces of the rubber member by using a plurality of joining devices. The plurality of devices are provided on the outside and inside of a forming drum and operate at the same time. However, this type of joining device also becomes large. A large space for installing the device is required. Moreover, a configuration of the forming drum also becomes complicated. As a result, a cost of the joining device becomes high.